Set standard logging prio to INFO

[amenk]

Most Mage core code and module use log() very seldomly, not for real debug messages.
Setting this to info would allow us to log also real debug info.

[verklov]

Hello amenk,
Sorry for the delay with the response.
Thank you for your contribution! Our team will review your pull request and respond as soon as our analysis is complete.

[verklov]

Hello amenk,
We cannot accept your pull request.
There is no reason to change default argument value in Logger::log() (god-class Mage no longer exists), because there will be no big difference in logged data.
As you may see in addStreamLog() in /lib/Magento/Logger.php the format of log is strictly defined and according to it this change is useless.
However if you still need to customize your logs you can add your own logger into the system, Magento allows that and provides such ability.
Nevertheless, thank you for your contribution and participation in the Magento product development!